<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>getSecondsDiffBetweenDates</title>
</head>

<body>
    <div>打开浏览器控制台查看结果</div>
    <script>
        const getSecondsDiffBetweenDates = (dateInitial, dateFinal) =>
            (dateFinal - dateInitial) / 1000;
        console.log(getSecondsDiffBetweenDates(
            new Date('2020-12-24 00:00:15'),
            new Date('2020-12-24 00:00:17')
        ));
    </script>
</body>

</html>